WO2020080260A1

WO2020080260A1 - Construction machine

Info

Publication number: WO2020080260A1
Application number: PCT/JP2019/040101
Authority: WO
Inventors: 佐藤　大和; 和也草野; 仁視西口; 邦彦池田; 健一羽野
Original assignee: 日立建機株式会社
Priority date: 2018-10-15
Filing date: 2019-10-10
Publication date: 2020-04-23
Also published as: US20210372431A1; JP2020063683A; EP3869044B1; JP7207933B2; CN112805474B; CN112805474A; US11680583B2; EP3869044A4; EP3869044A1

Abstract

A construction machine equipped with a centrifugal fan and a bell mouth arranged on the suction side of the centrifugal fan. The centrifugal fan has a rotatable hub, an annular shroud having a suction opening arranged so as to face the hub, and a plurality of blades provided between the hub and the shroud. An outflow opening of the bell mouth is arranged farther radially inward than the suction opening of the shroud. The blades are formed such that the front edge has a convex shape on a negative-pressure-surface side relative to a line segment connecting a portion of the front edge connected to the hub and a portion of the front edge connected to the shroud, and when the suction side of the centrifugal fan is viewed from the axial direction, the apex of the convex shape of the front edge is located farther radially inward than a wall surface of the outflow opening of the bell mouth.

Description

Construction machinery

The present invention relates to a construction machine, and more particularly, to a construction machine equipped with a centrifugal fan.

In construction machines such as hydraulic excavators and dump trucks, various equipment such as engines and heat exchangers are cooled by cooling air generated by a cooling fan. Inside the construction machine, a large number of devices and parts are arranged densely. When the cooling air is supplied to such an area, the pressure loss of the cooling air becomes large, so a centrifugal fan may be adopted as the cooling fan. Centrifugal fans generally provide a higher pressure rise at the same speed than axial fans.

The centrifugal fan is a disk-shaped hub (main plate) attached to a rotary drive shaft, a plurality of blades whose one end side is fixed to the outer peripheral portion of the hub at intervals in the circumferential direction, and the above-mentioned blades of the plurality of blades. A ring-shaped shroud (side plate) that is attached to the other end opposite to the hub and that forms an air suction port is provided on one side. Some of such centrifugal fans are intended to form a smooth flow on both sides of the blade to exert effective blade performance (for example, refer to Patent Document 1).

In the centrifugal fan described in Patent Document 1, the shroud is configured to have an arcuate cross-section that is inclined from the central air suction port toward the outer peripheral centrifugal direction with a predetermined curvature, and the shroud-side end portion between the hub of the blade and the shroud is formed. It is curved in the direction opposite to the rotation side. With the above configuration, the cross-sectional area of the corner portion formed between the airflow guide surface inside the shroud and the pressure surface of the blade is expanded more than when the blade is connected to the shroud by extending in a substantially straight line. , Dead water area reduction space is formed. Further, in the centrifugal fan described in Patent Document 1, a bell mouth is installed on the suction side of the centrifugal fan in order to smoothly guide air to the air suction port of the centrifugal fan. The bell mouth is arranged with the end portion of the air outlet on the downstream side loosely fitted inside the air inlet of the shroud.

JP, 2009-174541, A

The centrifugal fan pressurizes the air by sucking it in from the axial direction and discharging it to the outside in the radial direction, so the flow of air inside the fan is suddenly diverted. The airflow is pushed toward the hub side by inertia when it is turned radially outward from the axial direction. Further, the airflow on the shroud side needs to be turned with a larger curvature than the airflow on the hub side, but it is pressed against the hub side without being able to follow the wall shape of the shroud. Therefore, at a position where the direction of the airflow is changed to the radial direction to some extent, in the span direction of the blade (direction from the hub side of the blade toward the shroud side), the velocity of the airflow on the hub side becomes larger than that on the shroud side. Distribution occurs. If the flow velocity difference between the hub side and the shroud side becomes large, the airflow will separate from the shroud. In this case, since the effective flow passage area inside the centrifugal fan is reduced, the performance of the centrifugal fan is deteriorated.

One way to make the flow velocity distribution in the span direction of the blades uniform is to reduce the curvature of the shroud of the centrifugal fan so that the air flow follows the inner wall surface of the shroud. However, in the construction machine, various devices and parts other than the engine and the heat exchanger are housed inside, and the installation space of the centrifugal fan is limited. Therefore, there is a demand for a centrifugal fan that is as thin as possible (short in the axial direction), and it is difficult to use a shroud that has a small curvature and is gently curved because it leads to an increase in size of the centrifugal fan.

Also, as another method for making the flow velocity distribution in the span direction of the blades uniform, there is a configuration in which the flow path length in the radial direction of the centrifugal fan is lengthened. However, in a construction machine, a heat exchanger is generally installed on the upstream side of the centrifugal fan, and in order to cool the heat exchanger efficiently, it is necessary to make the suction fan area of the centrifugal fan as large as possible. is there. Further, in the construction machine, as described above, since the installation space of the centrifugal fan is limited, the outer diameter of the centrifugal fan is also limited according to the installation space. If the area of the suction port of the centrifugal fan is increased, the distance from the opening edge of the suction port of the centrifugal fan to the outer peripheral edge of the discharge side will be shortened accordingly. It is difficult to extend the road length.

By the way, in a construction machine equipped with a centrifugal fan, as in the centrifugal fan described in Patent Document 1, a bell mouth is installed on the suction side of the centrifugal fan, and the air outlet of the bell mouth is connected to the shroud of the centrifugal fan. Some are located on the inner peripheral side of the air inlet. In a bell mouth whose diameter is reduced toward the centrifugal fan side, the velocity of the air flowing out from the air outlet is higher on the wall surface side (radial outer side) than on the center side (radial inner side) of the bell mouth.

Also, a gap is provided between the rotating centrifugal fan and the stationary bell mouth so that they do not come into contact with each other. A part of the air discharged from the centrifugal fan flows into the centrifugal fan again as a leak flow through the gap. The centrifugal fan mounted on the construction machine has a centrifugal fan and a bell mouth compared to the centrifugal fan applied to the ceiling-embedded air conditioner as disclosed in Patent Document 1 in consideration of vehicle body vibration during operation. It is necessary to increase the gap. The larger the gap, the more leakage flow into the centrifugal fan.

Due to the influence of the wall shape of the bell mouth and the influence of the leakage flow, an air flow having a higher velocity flows into the air inlet of the centrifugal fan near the wall of the shroud than at the center of the air inlet. That is, the air flowing into the air suction port is locally accelerated near the wall surface of the shroud. Therefore, when the airflow near the wall surface of the shroud is turned radially outward from the axial direction, the inertia increases due to the increased speed, so that the airflow is pressed further toward the hub side. Therefore, in a centrifugal fan with a bell mouth installed on the suction side, a flow velocity distribution in the span direction is generated at a position where the airflow direction is radially diverted to some extent, in which the speed difference between the hub-side airflow and the shroud-side airflow is further increased. . With such a flow velocity distribution, the air flow is easily separated from the shroud.

From the above, in order to improve the performance of the centrifugal fan mounted on the construction machine, it is necessary to mitigate the flow velocity distribution in the span direction of the biased blades where the air flow velocity on the hub side becomes larger than that on the shroud side. .

In the centrifugal fan described in Patent Document 1, the end portion of the blade on the shroud side is curved in the direction opposite to the rotation direction, so that the corner portion formed between the airflow guide surface on the inner surface of the shroud and the positive pressure surface of the blade is disconnected. The area is expanding. However, in the configuration in which the cross-sectional area of the local region on the shroud side such as the corner portion is enlarged, only the deviation of the air flow generated from the axial direction from the shroud side to the hub side is locally generated. It seems that it cannot be suppressed.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a flow velocity distribution in the span direction of a blade with a bias such that the velocity of the air flow on the hub side in a centrifugal fan becomes larger than that on the shroud side. It is to provide construction machinery that can be mitigated.

The present application includes a plurality of means for solving the above problems, and one example thereof is a centrifugal fan housed inside a vehicle body, and a bell mouth arranged on the suction side of the centrifugal fan and having an outlet. Wherein the centrifugal fan is rotatable about an axis of rotation and a hub that is disposed so as to face the hub to form a flow path between the hub and an annular shroud that has a suction port. A plurality of blades provided at intervals in the circumferential direction between the hub and the shroud, and each of the plurality of blades has a front edge on the side where air flows in and a side where air flows out. A trailing edge, a wing surface on one side extending between the leading edge and the trailing edge, and a pressure surface facing forward with respect to a rotation direction, and between the leading edge and the trailing edge. The other side of the wing extending toward the rear side with respect to the rotation direction In the construction machine including the pressure surface, the outflow port of the bell mouth is arranged radially inward of the suction port of the shroud, each of the plurality of blades, the front edge is the With respect to a line segment that connects a connecting portion of the front edge with the hub and a connecting portion of the front edge with the shroud, the convex portion of the front edge is formed so as to have a convex shape on the suction surface side. The apex of the shape is formed so as to be located radially inward of the wall surface of the outlet of the bell mouth when the suction side of the centrifugal fan is viewed in the axial direction.

According to the present invention, the blade is configured so as to be positioned radially inward of the wall surface of the outlet of the bell mouth when the apex of the convex shape on the suction side at the front edge of the blade of the centrifugal fan is viewed from the axial direction. Therefore, it is possible to suppress the movement of the air flowing into the centrifugal fan from the vicinity of the wall surface of the bell mouth toward the hub side due to the inertia when the flow is outwardly in the radial direction. As a result, in the centrifugal fan mounted on the construction machine, it is possible to reduce the flow velocity distribution in the span direction of the blades in which the velocity of the air flow on the hub side tends to be higher than that on the shroud side.
Problems, configurations, and effects other than the above will be clarified by the following description of the embodiments.

It is a side view showing a hydraulic excavator as a first embodiment of a construction machine of the present invention. FIG. 2 is a partial cross-sectional view of the hydraulic excavator shown in FIG. 1 as viewed from the direction of arrow II-II, showing a state in which a part of the machine chamber of the hydraulic excavator is omitted. It is the figure which looked at the suction side of the centrifugal fan which constitutes a part of 1st Embodiment of the construction machine of this invention from the axial direction. It is a figure which shows the centrifugal fan shown in FIG. 3 in the state which removed the shroud. It is an enlarged view of the area | region shown by the code | symbol L of FIG. 3, and is a figure which shows the front edge of the blade of a centrifugal fan, and the vicinity of a front edge. FIG. 6 is a perspective view of the centrifugal fan shown in FIG. 4 as viewed from the direction of arrows VI-VI, showing a blade shape of the centrifugal fan. FIG. 7 is a cross-sectional view of the centrifugal fan shown in FIG. 3 as viewed from the arrow VII-VII (a cross-sectional view taken along a cylindrical surface around the rotation axis at the position of the connecting portion between the front edge of the blade and the shroud). FIG. 8 is a cross-sectional view of the centrifugal fan shown in FIG. 3 as viewed from the direction of arrows VIII-VIII (cross-sectional view cut along a cylindrical surface around the rotation axis at a position near the center of the blade in the chord direction). FIG. 4 is a cross-sectional view of the centrifugal fan shown in FIG. 3 viewed from the arrow IX-IX (a cross-sectional view taken along a cylindrical surface centering on the rotation axis at a position near the trailing edge of the blade). It is explanatory drawing which shows the radial velocity distribution of the airflow which passes the centrifugal fan suction opening in 1st Embodiment of the construction machine of this invention. It is explanatory drawing which shows the speed triangle in the hub side position (position H shown in FIG. 10) of the blade leading edge of the centrifugal fan in 1st Embodiment of the construction machine of this invention. It is explanatory drawing which shows the speed triangle in the position (position M shown in FIG. 10) near the span direction center of the blade leading edge of the centrifugal fan in 1st Embodiment of the construction machine of this invention. It is explanatory drawing which shows the speed triangle in the shroud side position (position S shown in FIG. 10) of the blade leading edge of the centrifugal fan in 1st Embodiment of the construction machine of this invention. FIG. 4 is an explanatory view showing a structure of a conventional centrifugal fan and an air flow of the conventional centrifugal fan, and is a perspective view seen from an arrow similar to arrow XVI-XVI shown in FIG. 3. It is explanatory drawing which shows the flow velocity distribution of the span direction in the front edge of the blade of a conventional centrifugal fan, the vicinity of the chord direction center, and the rear edge. FIG. 4 is an explanatory view showing the flow from the leading edge of the blade to the vicinity of the center in the chord direction in the centrifugal fan of the first embodiment of the construction machine of the invention, and is a perspective view seen from the arrow XVI-XVI shown in FIG. 3. is there. It is explanatory drawing which shows the flow of the air from the chord direction center vicinity of a blade | wing to the trailing edge in the centrifugal fan of 1st Embodiment of the construction machine of this invention. It is a figure which shows the analysis result of the flow field along the positive pressure surface of the blade of the centrifugal fan in 1st Embodiment of the construction machine of invention. It is a figure which shows the flow of the air inside the centrifugal fan in 1st Embodiment of the construction machine of invention. It is a figure which shows the flow of the air inside the centrifugal fan in the 1st modification of 1st Embodiment of the construction machine of invention. It is a figure which shows the flow of the air inside the centrifugal fan in the 2nd modification of 1st Embodiment of the construction machine of invention. It is sectional drawing shown in the state which abbreviate | omitted a part of the machine chamber in 2nd Embodiment of the construction machine of invention. It is sectional drawing shown in the state which abbreviate | omitted a part of the machine chamber in 3rd Embodiment of the construction machine of invention.

Hereinafter, an embodiment of the construction machine of the present invention will be described with reference to the drawings. In the present embodiment, a hydraulic excavator will be described as an example of a construction machine.

First, the configuration of a hydraulic excavator as a first embodiment of the construction machine of the present invention will be described with reference to FIGS. 1 and 2. 1 is a side view showing a hydraulic excavator as a first embodiment of a construction machine of the present invention, and FIG. 2 is a partial sectional view of the hydraulic excavator shown in FIG. It is a figure which shows in the state which abbreviate | omitted a part of machine room of. Here, the description will be given using the direction viewed from the operator seated in the driver's seat. In FIG. 2, thick arrows indicate the flow of air.

In FIG. 1, the hydraulic excavator 1 is provided with a crawler-type lower traveling body 2 that can be self-propelled, and an upper revolving body 3 that is rotatably mounted on the lower traveling body 2. The undercarriage 2 and the upper revolving superstructure 3 form a vehicle body. A work front 4 is provided at the front end of the upper swing body 3 so that the work front 4 can be lifted and lowered. The work front 4 is a multi-joint type actuating device for performing excavation work and the like, and includes, for example, a boom 6, an arm 7, and a bucket 8. The base end side of the boom 6 is rotatably connected to the front end of the upper swing body 3. The base end of the arm 7 is rotatably connected to the tip of the boom 6. The base end of the bucket 8 is rotatably connected to the tip of the arm 7. The boom 6, the arm 7, and the bucket 8 are driven by a boom cylinder 6a, an arm cylinder 7a, and a bucket cylinder 8a, which are hydraulic drive devices, respectively.

The upper revolving structure 3 includes a revolving frame 11 which is a support structure mounted on the lower traveling structure 2 so as to be revolvable, a cab 12 installed on the left front side of the revolving frame 11, and a rear end portion of the revolving frame 11. The counter weight 13 is provided at the right end in FIG. 1, and the machine room 14 is disposed between the cab 12 and the counter weight 13. The cab 12 is provided with an operating device for instructing operations of the lower traveling body 2, the work front 4, and the like, a driver's seat on which an operator is seated, and the like (both not shown). The counter weight 13 is for balancing the weight with the work front 4.

As shown in FIG. 2, for example, the machine room 14 accommodates a large number of devices including an engine 20 as a prime mover, a hydraulic pump (not shown) driven by the engine 20, and a cooling device 30 for cooling the engine 20. Has been done. An outer shell of the machine room 14 is formed by a building cover 16. The building cover 16 is provided with a suction port (not shown) that takes in outside air into the machine room 14 and a discharge port (not shown) that discharges air from the machine room 14.

The cooling device 30 is provided with a centrifugal fan 31 that produces cooling air, a bell mouth 32 that is disposed on the suction side of the centrifugal fan 31, and that rectifies air and guides it to the centrifugal fan 31, and cooling air produced by the centrifugal fan 31. And a heat exchange device 33 configured to operate. The centrifugal fan 31 is attached to the rotating shaft 23. The rotating shaft 23 is rotatably supported by the engine 20 above the drive shaft 20a of the engine 20. The drive shaft 20a and the rotary shaft 23 of the engine 20 are provided with a first pulley 24 and a second pulley 25, respectively. A belt 26 is stretched around the first pulley 24 and the second pulley 25. With such a configuration, the centrifugal fan 31 is rotationally driven by the engine 20 about the rotation axis A.

The bell mouth 32 has a shape in which the cross section of the flow passage is reduced toward the centrifugal fan 31 side. The upstream (left side in FIG. 2) end of the bell mouth 32 is attached to, for example, a device inside the machine room 14 or a building cover 16. The opening at the end of the bell mouth 32 on the side of the centrifugal fan 31 (on the right side in FIG. 2) constitutes an outlet 32a for the flow of air. The outlet 32a of the bell mouth 32 is arranged inside the suction port 31a of the centrifugal fan 31 in the radial direction with a gap D therebetween.

The heat exchange device 33 is arranged, for example, on the upstream side (left side in FIG. 2) of the bell mouth 32. The heat exchange device 33 is composed of, for example, a heat exchanger such as a radiator or an oil cooler. The radiator cools the cooling water of the engine 20, and the oil cooler cools the hydraulic oil supplied to the hydraulic drive system including the

hydraulic cylinders

6a, 7a, 8a (see FIG. 1) of the work front 4. .

A rectifying member 35 is arranged on the opposite side of the bell mouth 32 with the centrifugal fan 31 interposed therebetween. That is, the rectifying member 35 is arranged on the opposite side of the suction port 31a of the centrifugal fan 31 to the back side of the hub 41 described later. The rectifying member 35 suppresses the rapid expansion of the airflow Fd discharged from the centrifugal fan 31 into the machine chamber 14, and is a member that extends at least radially outward from the outer peripheral edge of the centrifugal fan 31. The rectifying member 35 is, for example, an annular flat plate member having an outer peripheral edge of a circular shape, an elliptic shape, a polygonal shape, or the like, and is fixed to the engine 20 via a stay 36. The rectifying member 35 also forms an air guide path for the air flow Fd discharged from the centrifugal fan 31 together with the bell mouth 32. The rectifying member 35 reduces a turning speed component by friction with the air flow Fd discharged from the centrifugal fan 31 to convert a part of kinetic energy of the air flow Fd into static pressure, though there is a loss due to the friction. It is possible to reduce the loss.

Next, the configuration of the centrifugal fan according to the first embodiment of the construction machine of the present invention will be described with reference to the drawings. First, the overall configuration of the centrifugal fan will be described with reference to FIGS. 3 is a view of the suction side of a centrifugal fan that constitutes a part of the first embodiment of the construction machine of the present invention as seen from the axial direction, and FIG. 4 shows the centrifugal fan shown in FIG. 3 with the shroud removed. FIG.

2 to 4, the centrifugal fan 31 is attached to the rotary shaft 23, and is a disk-shaped hub 41 that is rotatable around the rotary axis A, and one side in the axial direction of the hub 41 (left side in FIG. 2). An annular shroud 42 that is arranged to face each other and is coaxial with the hub 41 and forms a flow path between the hub 41 and the hub 41 is provided at a predetermined interval in the circumferential direction between the hub 41 and the shroud 42. And a plurality of blades 43. As shown in FIGS. 2 and 3, the shroud 42 is formed such that the axial one side (left side in FIG. 2) has a smaller diameter than the other side (right side in FIG. 2). In the shroud 42, an opening having a small diameter located at the center on one axial side constitutes the suction port 31 a of the centrifugal fan 31.

Next, the shape of the centrifugal fan blades will be described with reference to FIGS. 2 to 9. 5 is an enlarged view of a region indicated by reference symbol L in FIG. 3, showing the leading edge and the vicinity of the leading edge of the blade of the centrifugal fan, and FIG. 6 is a perspective view of the centrifugal fan shown in FIG. FIG. 7 is a perspective view showing the blade shape of the centrifugal fan, and FIG. 7 is a cross-sectional view of the centrifugal fan shown in FIG. 3 as seen from the arrow VII-VII (rotating at the position of the connecting portion between the front edge of the blade and the shroud). FIG. 8 is a sectional view of the centrifugal fan shown in FIG. 3 as viewed from the direction of arrows VIII-VIII (centering around the rotation axis at a position near the blade chord direction center). 9 is a cross-sectional view taken along the line IX-IX of the centrifugal fan shown in FIG. 3 (a cross-sectional view taken along the line IX-IX of the centrifugal fan shown in FIG. 3). FIG.

As shown in FIGS. 2 and 4, each blade 43 extends between a front edge 44 on the air inflow side, a rear edge 45 on the air outflow side, and between the front edge 44 and the rear edge 45. And a blade on the other side (a back surface side of the pressure surface 46) extending between the front edge 44 and the trailing edge 45, which is the blade surface on one side and faces the front side with respect to the rotation direction R. And a negative pressure surface 47 facing the rear side with respect to the rotation direction R. The direction in which the blade 43 extends from the connection portion with the hub 41 to the connection portion with the shroud 42 is defined as the span direction of the blade 43. Further, the direction of the blade 43 extending from the leading edge 44 to the trailing edge 45 is defined as the chord direction of the blade 43.

As shown in FIGS. 3 to 5, at the front edge 44 of each blade 43, the connecting portion 44h with the hub 41 is located radially inward of the connecting portion 44s with the shroud 42. In addition, as shown in FIGS. 5 and 6, the front edge 44 is located on the negative pressure surface 47 side (in the rotation direction R) with respect to the line segment SL connecting the connection portion 44h with the hub 41 and the connection portion 44s with the shroud 42. It is curved so as to be convex toward the rear side). Furthermore, as shown in FIGS. 3 and 5, each blade 43 has a convex vertex 44v of the front edge 44 when the suction side of the centrifugal fan 31 is viewed in the axial direction thereof, and the outlet 32a of the bell mouth 32. It is configured so as to be located on the inner side in the radial direction (on the side of the rotation axis A) than the wall surface.

As shown in FIGS. 4 and 6, the blade 43 is configured such that the convex shape of the leading edge 44 curved toward the suction surface 47 extends in the chord direction to reach the trailing edge 45. That is, as shown in FIGS. 7 to 9, the blade 43 has a cross section from a front edge 44 to a rear edge 45, which is cut along a cylindrical surface centering on the rotation axis A, at a connecting portion with the hub 41 of the blade 43 ( With respect to the line segment S connecting the root part) 43h and the connecting part (tip part) 43s of the blade 43 to the shroud 42, the negative pressure surface 47 side (rear side with respect to the rotation direction R) should be convex. It is curved.

As shown in FIGS. 7 and 8, the blade 43 has a curvature of the apex 43v in the above-mentioned convex shape at a position near the center in the chord direction from the leading edge 44 (a position midway between the leading edge 44 and the trailing edge 45). It is configured to gradually increase toward the end. In addition, as shown in FIGS. 8 and 9, in the blade 43, the curvature of the apex 43v in the convex shape is from the position near the center in the chord direction (the middle position between the leading edge 44 and the trailing edge 45) to the rear. It is configured to gradually decrease toward the edge 45. That is, the blade 43 is located on the leading edge 44 side, and the first curved blade portion whose curvature of the apex 43v in the convex shape of the blade 43 is gradually increased from the leading edge 44 is located on the trailing edge 45 side. In the convex shape of the second curved blade portion, the curvature of the apex 43v gradually decreases toward the trailing edge 45.

Further, as shown in FIGS. 7 to 9, the blades 43 are arranged in the circumferential direction of the connecting portion 43s with the shroud 42 with respect to the connecting portion 43h with the hub 41 in the blade cross section cut along the cylindrical surface with the rotation axis A as the center. The relative position is configured to be gradually displaced rearward with respect to the rotation direction R from the front edge 44 toward the rear edge 45. More specifically, in the blade cross section near the front edge 44 of the blade 43, as shown in FIG. 7, the circumferential position of the connecting portion 43s with the shroud 42 is greater than the circumferential position of the connecting portion 43h with the hub 41. Is also displaced forward with respect to the rotation direction R. In the blade cross section near the center of the chord direction of the blade 43, as shown in FIG. 8, the circumferential position of the connecting portion 43s with the shroud 42 is substantially the same as the circumferential position of the connecting portion 43h with the hub 41. Is. In the blade cross section near the trailing edge 45 of the blade 43, as shown in FIG. 9, the circumferential position of the connecting portion 43s with the shroud 42 is in the rotational direction R rather than the circumferential position of the connecting portion 43h with the hub 41. On the other hand, it is displaced to the rear side. As described above, from the vicinity of the front edge 44 to the position near the center of the chord direction, the circumferential relative position of the connection portion 43s with the shroud 42 with respect to the connection portion 43h with the hub 41 is forward with respect to the rotation direction R. Deviated. On the other hand, from the position near the center in the chord direction to the trailing edge 45, the relative position in the circumferential direction of the connecting portion 43s with the shroud 42 with respect to the connecting portion 43h with the hub 41 is displaced rearward with respect to the rotation direction R. .

Next, the setting of the blade inlet angle in the centrifugal fan will be described with reference to FIGS. 10 to 13. FIG. 10 is an explanatory view showing the radial velocity distribution of the air flow passing through the centrifugal fan suction port in the first embodiment of the construction machine of the present invention, and FIG. 11 is the first embodiment of the construction machine of the present invention. 12 is an explanatory view showing a speed triangle at a hub side position (position H shown in FIG. 10) of the blade leading edge of the centrifugal fan in FIG. 12, and FIG. 12 is a blade front of the centrifugal fan in the first embodiment of the construction machine of the present invention. Explanatory drawing showing a speed triangle at a position near the center of the edge in the span direction (position M shown in FIG. 10), and FIG. 13 is a shroud side of the blade leading edge of the centrifugal fan in the first embodiment of the construction machine of the present invention. FIG. 11 is an explanatory diagram showing a velocity triangle at the position (position S shown in FIG. 10).

In the present embodiment, as shown in FIG. 10, a bell mouth 32 is installed on the suction side of the centrifugal fan 31, and there is a gap between the suction port 31a of the centrifugal fan 31 and the outflow port 32a of the bell mouth 32. D is provided. In this case, a part of the air discharged from the centrifugal fan 31 passes through the gap D between the centrifugal fan and the bellmouth and again flows into the centrifugal fan as a leakage flow FL. Further, since the bell mouth 32 is reduced in diameter toward the outflow port 32a side, the velocity of the air flowing out from the outflow port 32a of the bell mouth 32 is closer to the wall surface side than the center side (radially inner side) of the bell mouth 32 ( It becomes larger in the radial direction) (see the flow velocity distribution shown in FIG. 10). That is, the velocity locally increases in the region near the wall surface of the outlet 32a of the bell mouth 32. Due to the influence of the bell mouth 32, in the suction port 31a of the centrifugal fan 31, a flow having a higher velocity flows into the vicinity of the wall surface of the shroud 42 than in the central portion.

In the present embodiment, the inlet angle of the blades 43 of the centrifugal fan 31 is set in consideration of the influence of the bell mouth 32 described above. The blade 43 is configured such that its inlet angle matches the inflow angle of air to the blade 43. In this case, since the flow of air flowing into the centrifugal fan 31 is a collision-free inflow condition, it is possible to reduce the collision loss of the flow. The inlet angle of the blades 43 is centered on the tangent line Ct at the front edge 44 of the warp line C of the sectional shape of the blades 43 shown in FIG. 11 and the rotation axis A (see FIG. 10) of the centrifugal fan 31. Is an angle formed with a tangent line It at the front edge 44 in an imaginary inscribed circle I that is in contact with the front edge 44 of the. The warp line is a curve obtained by sequentially connecting the midpoints of the positive pressure surface 46 and the negative pressure surface 47 of the blade 43. The inflow angle is an angle formed by the relative inflow velocity vector of the airflow and the rotation direction R of the centrifugal fan 31.

Specifically, at the position H (see FIG. 10) on the hub 41 side at the front edge 44 of the blade 43, as shown in FIG. 11, it is obtained from the peripheral speed Uh of the blade 43 and the absolute speed Cah of the air flow. The airflow having the relative inflow speed Wh flows in. The peripheral speed Uh is determined from the rated rotation speed of the centrifugal fan 31 and the radial distance from the rotation axis A to the position H (see the double-headed arrow shown in FIG. 10). The meridional velocity Cmh is equal to the absolute velocity Cah because it is assumed that the airflow flowing from the inside of the bell mouth 32 into the suction port 31a of the centrifugal fan 31 has no pre-turning. Therefore, the inlet angle kh of the blade 43 at the position H is set to match the inflow angle βh obtained by the relative inflow velocity Wh determined by the peripheral velocity Uh and the meridional direction velocity Cmh.

At a position M (see FIG. 10) near the center in the span direction at the leading edge 44 of the blade 43, as shown in FIG. 12, an airflow having a relative inflow speed Wm determined by the peripheral speed Um of the blade 43 and the absolute speed Cam of the airflow. Flows in. The peripheral speed Um is determined from the rated rotation speed of the centrifugal fan 31 and the radial distance from the rotation axis A to the position M. The peripheral speed Um at the position M is higher than the peripheral speed Uh at the position H because the position M is located radially outside the position H (see FIG. 10). The meridional surface speed Cmm is larger than the meridional surface speed Cmh (see FIG. 11) at the position H due to the influence of the acceleration on the wall surface of the bell mouth 32 (see the flow velocity distribution shown in FIG. 10). The meridional plane velocity Cmm is equal to the absolute velocity Cam without the pre-turning as in the case of the position H. Therefore, the blade entrance angle km at the position M is set so as to match the inflow angle βm obtained by the relative inflow velocity Wm determined by the peripheral velocity Um and the meridional direction velocity Cmm.

At the position S on the shroud 42 side of the front edge 44 of the blade 43, as shown in FIG. 10, the leakage flow FL flows from the gap D between the bell mouth 32 and the shroud 42 into the suction port 31a of the centrifugal fan 31. Since this leak flow FL is the air flow discharged from the centrifugal fan 31, it has a swirl velocity component. Therefore, there is a pre-turn in the flow of air flowing into the position S. That is, as shown in FIG. 13, the absolute velocity Cas of the airflow is not equal to the meridional velocity Cms, and the absolute velocity Cas includes the turning velocity Cus. Therefore, at the position S (see FIG. 10) on the shroud 42 side of the front edge 44 of the blade 43, the flow having the relative inflow speed Ws determined by the absolute speed Cas including the turning speed Cus and the peripheral speed Us of the blade 43 flows in. . The peripheral speed Us is determined from the rated rotation speed of the centrifugal fan 31 and the radial distance from the rotation axis A to the position S. The peripheral speed Us at the position S is higher than the peripheral speed Um at the position M because the position S is located radially outside the position M (see FIG. 10). The absolute velocity Cas is obtained from the meridional velocity Cms and the turning velocity Cus. The meridional surface speed Cms is higher than the meridional surface speed Cmh at the position H (see FIG. 11) due to the influence of the acceleration on the wall surface of the bell mouth 32 (see the flow velocity distribution shown in FIG. 10). The inlet angle ks at the position S is set so as to match the inflow angle βs obtained by the inflow relative velocity Ws determined by the peripheral velocity Us and the absolute velocity Cas.

Next, the flow and effect of the air inside the centrifugal fan in the first embodiment of the construction machine of the present invention will be described while comparing with the conventional centrifugal fan. First, the structure of a conventional centrifugal fan and the internal air flow will be described with reference to FIGS. 10, 14 and 15. 14 is an explanatory view showing the structure of a conventional centrifugal fan and the air flow of the conventional centrifugal fan. FIG. 14 is a perspective view seen from an arrow similar to arrow XVI-XVI shown in FIG. 3, and FIG. It is explanatory drawing which shows the flow velocity distribution of the span direction in the front edge of the blade of a centrifugal fan, the center of a chord direction, and a rear edge. In FIG. 14, thick arrows indicate the flow of air. In FIG. 15, the flow velocity distribution is indicated by a plurality of arrows. Note that, in FIGS. 14 and 15, the same reference numerals as those shown in FIGS. 1 to 14 denote the same parts, and thus detailed description thereof will be omitted.

In the conventional centrifugal fan 131, as shown in FIG. 14, the end of the blade 143 on the shroud 42 side in the span direction is curved rearward with respect to the rotation direction R. That is, the front edge 144 of the blade 143 is located on the suction surface 147 side (rear side with respect to the rotation direction R) with respect to the line segment SL connecting the connection portion 144h with the hub 41 and the connection portion 144s with the shroud 42. It is curved so as to have a convex shape. The blade 143 is configured such that the position of the convex-shaped apex 144v of the front edge 144 is near the shroud 42 side.

Since the centrifugal fan 131 sucks air from the axial direction (upward direction in FIG. 14) and discharges it to the outside in the radial direction, the air flow inside the fan is suddenly turned. This airflow is pushed toward the hub 41 side by inertia when it is turned radially outward from the axial direction. Further, the airflow on the shroud 42 side needs to be turned with a larger curvature than the airflow on the hub 41 side, but the airflow on the side of the shroud 42 is pressed against the hub 41 side without being able to follow the wall shape of the shroud 42.

In the blade 143 of the conventional centrifugal fan 131 described above, since the blade 143 is curved so as to have a convex shape on the negative pressure surface 147 side, the influence of the pressing of the air flow on the hub 41 side depends on the blade surface shape of the blade 143. Will be alleviated. However, since the position of the apex 144v in the convex shape of the blade 143 is near the shroud 42 side, the influence of pressing on the hub 41 side is mitigated only for the airflow near the shroud 42 side. Therefore, the influence of pressing the air flow on the hub 41 side cannot be sufficiently mitigated, and at the radial position where the direction of the air flow is radially displaced to some extent, in the span direction of the blades 143, the flow velocity on the hub 41 side is shroud 42. There is a biased flow velocity distribution that is larger than on the side.

Specifically, the flow velocity distribution is as follows. As shown in FIG. 15, a conventional centrifugal fan 131 has a bell mouth 32 arranged on the suction side, as in the present embodiment. The flow velocity distribution in the meridional cross section of the outlet 32a of the bell mouth 32 is larger than the center side (rotation axis A side) of the flow velocity near the wall surface of the bell mouth 32 (see the flow velocity distribution shown in FIG. 10). . Therefore, even in the suction port 131a of the conventional centrifugal fan 131, the flow velocity distribution on the shroud 42 side is higher than that on the hub 41 side.

At the front edge 144 of the conventional blade 143, as shown in FIG. 15, the air flow is pressed against the hub 41 side, so that the velocity difference between the shroud 42 side and the hub 41 side is reduced, resulting in a flow velocity distribution. That is, the flow velocity distribution in the span direction at the front edge 144 is made more uniform than the flow velocity distribution in the radial direction at the suction port 131a.

On the other hand, in the first half of the flow path from the front edge 144 to the vicinity of the center of the chord direction, the air flow continues to be pressed to the hub 41 side by the turning of the air flow from the axial direction to the radially outer side. Therefore, at the position near the center (the position indicated by the chain double-dashed line in FIG. 15), a flow velocity distribution in the span direction gradually decreases from the hub 41 side toward the shroud 42 side. When a flow velocity distribution in which the speed difference between the hub 41 side and the shroud 42 side is abruptly changed is generated, the air flow cannot be along the shroud 42 and becomes the flow Fs separated from the shroud 42.

Also, in the latter half of the flow path from the vicinity of the center of the chord direction to the trailing edge 145, the turning of the air flow has ended, so the air flow is not pressed toward the hub 41 side. Therefore, the trailing edge 145 of the blade 143 has substantially the same flow velocity distribution in the span direction near the center of the chord direction. That is, the flow velocity distribution in the span direction at the trailing edge 145 is a distribution that gradually decreases from the hub 41 side toward the shroud 42 side.

Thus, the conventional centrifugal fan 131 cannot effectively reduce the speed difference between the hub 41 side and the shroud 42 side. That is, it is difficult to improve the fan characteristic in which the flow rate is biased toward the hub 41 side at the trailing edge 145 of the blade 143.

Next, the air flow and effect of the centrifugal fan in the first embodiment of the construction machine of the present invention will be described with reference to FIGS. 5 and 16 to 19. FIG. 16 is an explanatory diagram showing a flow from the leading edge of the blade to the vicinity of the center in the chord direction in the centrifugal fan according to the first embodiment of the construction machine of the invention, which is viewed from the arrow XVI-XVI shown in FIG. 17 is a perspective view, FIG. 17 is an explanatory view showing the air flow from the vicinity of the center of the blade chord direction to the trailing edge in the centrifugal fan of the first embodiment of the construction machine of the invention, and FIG. 18 is the construction machine of the invention. The figure which shows the analysis result of the flow field along the positive pressure surface of the blade of the centrifugal fan in 1st Embodiment, FIG. 19 is the figure which shows the air flow inside the centrifugal fan in 1st Embodiment of the construction machine of this invention. Is. 16 and 17, thick arrows indicate the flow. In FIG. 18, white arrows indicate the direction of flow. In FIG. 19, a black dot indicates a position where the curvature of the apex of the curved convex shape of the blade is maximum.

In the present embodiment, as shown in FIGS. 5 and 16, the front edge 44 of the blade 43 is curved so as to be convex toward the suction surface 47 side (rear side with respect to the rotation direction R). Furthermore, when the suction side of the centrifugal fan 31 is viewed from the axial direction, the blades are arranged so that the position of the convex vertex 44v of the front edge 44 is located radially inward of the wall surface of the outlet 32a of the bell mouth 32. 43 is configured. That is, the position of the convex vertex 44v of the front edge 44 is closer to the hub 41 side than the position of the convex vertex 144v of the front edge 144 in the blade 143 of the conventional centrifugal fan 131 shown in FIG. Due to the shape of the front edge 44, in the flow of air that has flowed into the suction port 31a of the centrifugal fan 31, it is possible to reduce the flow rate that moves toward the hub 41 side by turning outward from the axial direction in the radial direction. In particular, as compared with the conventional centrifugal fan 131 (see FIG. 14), as shown in FIG. 16, it is possible to suppress the movement of the air flow near the center in the span direction to the hub 41 side, and at the same time, to reduce the air flow on the hub 41 side. It is possible to move a part of the area near the center in the span direction.

Furthermore, in the present embodiment, as shown in FIG. 16, the convex shape of the leading edge 44 extends in the chord direction, and the curvature of the apex in the convex shape is located at a position near the center of the chord direction from the leading edge 44. The blades 43 are configured so as to gradually increase toward. Due to the curved shape of the blades 43 as described above, compared to the conventional centrifugal fan 131 (see FIG. 14), the movement of the air flow on the hub 41 side to the hub 41 side due to the turning outward from the axial direction in the radial direction is suppressed. Therefore, the airflow can be collected near the apex of the convex shape near the center of the chord direction.

In addition, in the present embodiment, as shown in FIG. 17, the convex shape of the leading edge 44 extends in the chord direction to the trailing edge 45, and the curvature of the apex of the convex shape is near the center of the chord direction. The blades 43 are configured so as to become gradually smaller from the position toward the trailing edge 45. Due to the curved shape of the blades 43, the airflow collected near the apex of the convex shape near the center of the chord direction can be diffused in the span direction on the trailing edge 45 side.

Furthermore, in the present embodiment, the relative position in the circumferential direction of the connecting portion 43s with the shroud 42 with respect to the connecting portion 43h with the hub 41 in the cross section of the blade 43 cut along the cylindrical surface centering on the rotation axis A is set to the front. The edge 44 is gradually displaced rearward with respect to the rotation direction R from the edge 45 to the trailing edge 45 (see FIGS. 7 to 9), and as shown in FIG. The blades 43 are configured such that the circumferential position of 43s is displaced rearward with respect to the rotation direction R with respect to the circumferential position of the connecting portion 43h with the hub 41. With such a shape of the blades 43, the airflow that tends to be biased toward the hub 41 side can be guided to the shroud 42 side and diffused in the span direction at the trailing edge 45.

As described above, in the present embodiment, the curvature of the apex of the convex shape on the suction surface 47 side extending from the leading edge 44 to the trailing edge 45 of the blade 43 is directed from the leading edge 44 to a position near the center in the chord direction. The curved shape of the blades 43 is defined so that the blades 43 gradually increase in size toward the trailing edge 45 from a position near the center of the chord direction, and that the blades 43 are connected to the connecting portion 43h with the hub 41. The relative position in the circumferential direction of the connecting portion 43s with the shroud 42 is gradually displaced toward the rear side in the rotational direction R from the front edge 44 toward the trailing edge 45, and the connecting portion with the shroud 42 at the trailing edge 45 of the blade 43 is formed. By defining the connection position of the blades 43 with respect to the hub 41 and the shroud 42 so that 43s is displaced rearward in the rotational direction R with respect to the connection portion 43h with the hub 41, as shown in FIG. The air flowing in from the vicinity of the apex 44v of the convex shape is collected on the side of the apex 43v of the convex shape in the process from the leading edge 44 to the vicinity of the center in the chord direction, and then guided to the shroud 42 side in the process of proceeding to the trailing edge 45. You can As a result, as shown in FIG. 19, in the first half of the flow path of the centrifugal fan 31, the flow rate of the air flow moving to the hub 41 side due to the turning outward from the axial direction in the first half of the flow path is reduced, and in the second half of the flow path. The airflow can be diffused in the span direction. Therefore, the flow velocity distribution in the span direction from the hub 41 side to the shroud 42 side at the trailing edge 45 can be made uniform. That is, it is possible to improve the fan characteristic (see FIG. 15) in which the flow rate is biased toward the hub 41 side at the discharge port of the conventional centrifugal fan 131.

As described above, according to the first embodiment of the construction machine of the present invention, when the convex vertex 44v is seen from the axial direction on the suction surface 47 side of the front edge 44 of the blade 43 of the centrifugal fan 31, Since the blades 43 are arranged so as to be located radially inward of the wall surface of the outlet 32a of the bell mouth 32, the flow of the air flowing into the centrifugal fan 31 from the vicinity of the wall surface of the bell mouth 32 is diverted radially outward. Movement toward the hub 41 side due to inertia at the time can be suppressed. As a result, in the centrifugal fan 31 mounted on the hydraulic excavator (construction machine) 1, the flow velocity distribution in the span direction of the blades 43 in which the velocity of the air flow on the hub 41 side tends to be higher than that on the shroud 42 side can be relaxed. it can.

Next, a first modified example and a second modified example of the first embodiment of the construction machine of the present invention will be described with reference to FIGS. 20 and 21. FIG. 20 is a diagram showing an air flow inside the centrifugal fan in the first modification of the first embodiment of the construction machine of the invention, and FIG. 21 is a second modification of the first embodiment of the construction machine of the invention. 6 is a diagram showing the flow of air inside the centrifugal fan in FIG. 20 and 21, a black dot indicates a position where the curvature of the apex of the curved convex shape of the blade is maximum. 20 and 21, the same reference numerals as those shown in FIGS. 1 to 19 denote the same parts, and thus detailed description thereof will be omitted.

The difference between the first modification of the first embodiment of the construction machine of the present invention shown in FIG. 20 and the first embodiment is that the curvature of the apex 43v in the curved convex shape of the blade 43 is maximum. Is not the position near the center of the chord direction (see FIG. 19) as in the first embodiment, but is near the trailing edge 45. Specifically, the blade 43 is configured such that the curvature of the apex of the convex shape gradually increases from the leading edge 44 to the vicinity of the trailing edge 45 (the position of the black dot). In addition, the blade 43 is configured such that the curvature of the apex of the convex shape gradually decreases from the vicinity of the trailing edge 45 (the position of the black dot) toward the trailing edge 45. In other words, the blade 43 includes the leading edge 44 to the vicinity of the trailing edge 45 (the position of the black dot), and the curvature of the apex of the convex shape of the blade 43 gradually increases from the leading edge 44 to the leading edge 44 side first curved blade. Portion and the vicinity of the trailing edge 45 (the position of the black dot) to the trailing edge 45, and the curvature of the apex of the convex shape of the blade 43 gradually decreases toward the trailing edge 45. It consists of and.

In this modification, the air that has flowed into the centrifugal fan 31 is collected on the apex side of the convex shape of the blade 43 in the process of reaching from the leading edge 44 to the vicinity of the trailing edge 45 (the position of the black dot), while at the trailing edge 45. In the process of reaching, it is guided to the shroud 42 side. As a result, the flow rate of the air flow moving to the hub 41 side can be reduced, and the air flow can be diffused in the span direction near the trailing edge 45. Therefore, it is possible to improve the fan characteristic (see FIG. 15) in which the flow rate is biased toward the hub 41 side at the discharge port of the conventional centrifugal fan 131.

However, in this modified example, the maximum position of the curvature of the apex of the convex shape of the blade 43 is shifted to the trailing edge 45 side as compared with the first embodiment, so that diffusion in the span direction at the trailing edge 45 is caused. This is insufficient as compared with the first embodiment. Therefore, the trailing edge 45 has a flow velocity distribution in which the flow velocity near the central portion in the span direction is higher than that on the hub 41 side and the shroud 42 side.

Further, the difference between the second modification of the first embodiment of the construction machine of the present invention shown in FIG. 21 and the first embodiment is that the curvature of the apex 43v in the curved convex shape of the blade 43 is different. Is not the position near the center of the chord direction (see FIG. 19) as in the first embodiment, but is near the leading edge 44. Specifically, the blade 43 is configured such that the curvature of the apex of the convex shape gradually increases from the front edge 44 toward the vicinity of the front edge 44 (the position of the black dot). In addition, the blade 43 is configured so that the curvature of the apex of the convex shape gradually decreases from the vicinity of the leading edge 44 (the position of the black dot) toward the trailing edge 45. In other words, the blade 43 includes the leading edge 44 to the vicinity of the leading edge 44 (the position of the black dot), and the curvature of the apex of the convex shape of the blade 43 gradually increases from the leading edge 44 to the leading edge 44 side first curved blade. Second curved blade portion on the trailing edge 45 side including the portion and the vicinity of the leading edge 44 (the position of the black dot) to the trailing edge 45, and the curvature of the apex of the convex shape of the blade 43 gradually decreases toward the trailing edge 45. It consists of and.

In this modification, the air that has flowed into the centrifugal fan 31 can be collected on the apex side of the convex shape of the blades 43 in the process from the leading edge 44 to the vicinity of the leading edge 44 (the position of the black dot). As a result, the flow rate of the airflow moving toward the hub 41 side due to the turning outward from the axial direction can be reduced. Therefore, it is possible to improve the fan characteristic (see FIG. 15) in which the flow rate is biased toward the hub 41 side at the discharge port of the conventional centrifugal fan 131.

However, in this modified example, the maximum position of the curvature of the apex of the convex shape of the blade 43 is shifted to the front edge 44 side as compared with the first embodiment, and is moved to the hub 41 side at the time of turning. The effect of reducing the flow rate of the air flow is smaller than that in the first embodiment. Therefore, at the trailing edge 45, the flow velocity on the hub 41 side becomes larger than that on the shroud 42 side. However, compared to the conventional centrifugal fan 131, the flow velocity difference between the hub 41 side and the shroud 42 side is reduced.

According to the first modified example and the second modified example of the first embodiment of the construction machine of the present invention described above, in front of the blades 43 of the centrifugal fan 31, the same effect as that of the first embodiment described above can be obtained. It is possible to suppress the movement of the air flowing into the edge 44 toward the hub 41 side due to the inertia when the flow is turned. As a result, the flow velocity distribution in the span direction of the blades 43 of the centrifugal fan 31 can be relaxed.

Next, a second embodiment of the construction machine of the present invention will be described with reference to FIG. FIG. 22 is a cross-sectional view showing the second embodiment of the construction machine of the present invention with a part of the machine chamber being omitted. Note that, in FIG. 22, the same reference numerals as those shown in FIGS. 1 to 21 denote the same parts, and thus detailed description thereof will be omitted.

The difference between the second embodiment of the construction machine of the present invention shown in FIG. 22 and the first embodiment is that the shape of the rectifying member is different. Specifically, the rectifying member 35 of the first embodiment is an annular flat plate member (see FIG. 2). On the other hand, the rectifying member 35A of the present embodiment is configured such that the portion radially outside the outer peripheral edge of the centrifugal fan 31 is inclined in the direction away from the centrifugal fan 31 with respect to the radial direction of the centrifugal fan 31. ing. That is, the rectifying member 35A has an annular flat plate portion 35b that extends radially inward of the outer peripheral edge of the centrifugal fan 31, and an annular flat plate portion 35b that is inclined from the outer peripheral edge of the flat plate portion 35b in a direction away from the centrifugal fan 31. It is composed of an inclined portion 35c.

According to the second embodiment of the construction machine of the present invention described above, the portion of the flow regulating member 35A radially outside the outer peripheral edge of the centrifugal fan 31 is separated from the centrifugal fan 31 in the radial direction of the centrifugal fan 31. Since the air flow Fd is inclined in the direction, a part of the air flow Fd discharged from the centrifugal fan 31 can be diverted from the radial direction to the axial direction side, and the collision of the air flow Fd with the building cover 16 can be mitigated.

Next, a third embodiment of the construction machine of the present invention will be described with reference to FIG. FIG. 23 is a cross-sectional view showing a state in which a part of a machine chamber in the third embodiment of the construction machine of the invention is omitted. Note that, in FIG. 23, the same reference numerals as those shown in FIGS. 1 to 22 denote the same parts, and thus detailed description thereof will be omitted.

The difference between the third embodiment of the construction machine of the present invention shown in FIG. 23 and the second embodiment is that the second rectifying member 38 is provided on the shroud 42 side so as to newly face the rectifying member 35A. It has been placed in. The second rectifying member 38 extends outward in the radial direction from the outer peripheral edge of the centrifugal fan 31, and is configured such that the radially outer end portion is located closer to the rectifying member 35A side than the radially inner end portion. . The second rectifying member 38 is attached to, for example, the building cover 16 located radially outside the centrifugal fan 31. The second rectifying member 38 forms an air guide path together with the rectifying member 35A, and turns the airflow Fd radially discharged from the centrifugal fan 31 in the axial direction to guide the airflow Fd along the building cover 16. The air guide passage may be formed as a diffuser for pressure recovery, for example.

According to the third embodiment of the construction machine of the present invention described above, the second rectifying member 38 is opposed to the rectifying member 35A, and the second rectifying member 38 is extended radially outward of the outer peripheral edge of the centrifugal fan 31. Since the air flow Fd discharged from the centrifugal fan 31 can be diverted in the axial direction because the radial outer end is located closer to the rectifying member 35A side than the radial inner end while being made to exist. The collision loss of Fd with the building cover 16 can be further reduced.

The present invention is not limited to this embodiment, and various modifications are included. The above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. A part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

For example, in the above-described embodiment of the construction machine of the present invention, an example in which the construction machine of the present invention is applied to the hydraulic excavator 1 has been shown, but the present invention is applicable to various construction machines such as a hydraulic crane and a wheel loader. It can be widely applied.

In the first embodiment described above, the curvature of the apex 43v in the convex shape of the blade 43 gradually increases from the leading edge 44 toward the position near the center of the chord direction, while An example is shown in which the blade 43 is configured so as to gradually decrease from the position toward the trailing edge 45. However, while maintaining the curvature of the apex 43v in the convex shape of the blade 43 from the leading edge 44 to the position near the center of the chord direction, the blade gradually decreases from the position near the center of the chord direction toward the trailing edge 45. Can also be configured. That is, the blade has a first curved blade portion on the leading edge 44 side where the curvature of the apex 43v in the convex shape of the blade 43 is kept the same from the leading edge 44, and a curvature of the apex 43v in the convex shape of the blade 43 is a trailing edge. It is also possible to configure with the second curved blade portion on the trailing edge 45 side that gradually decreases toward 45.

In the first and second modified examples of the first embodiment described above, the curvature of the convex vertex 43v of the blade 43 is changed from the leading edge 44 to the vicinity of the trailing edge 45 or the vicinity of the leading edge 44. An example is shown in which the blades 43 are configured such that the blades 43 gradually increase in size while gradually decreasing from the vicinity of the trailing edge 45 or the vicinity of the leading edge 44 toward the trailing edge 45. However, the curvature of the apex 43v in the convex shape of the blade 43 is maintained from the leading edge 44 to the vicinity of the trailing edge 45 or to the vicinity of the leading edge 44, while the curvature from the vicinity of the trailing edge 45 or the vicinity of the leading edge 44 toward the trailing edge 45. It is also possible to configure the blade 43 so that it gradually becomes smaller.

Further, in the above-described embodiment, an example of the configuration (annular member) in which the

flow regulating members

35, 35A and the second flow regulating member 38 are arranged around the entire circumference of the centrifugal fan 31 is shown, but the

flow regulating members

35, 35A are shown. It is also possible to use the rectifying member and the second rectifying member that are arranged only on a part of the outer peripheral side of the centrifugal fan 31 in consideration of the installation space of the second rectifying member 38, the manufacturing cost, the ease of attachment, and the like. is there.

Further, in the above-described first and second embodiments, the example in which the rectifying

members

35 and 35A are fixed to the engine 20 via the stay 36 is shown, but the rectifying member may be part of the engine 20. Is. However, fixing the rectifying

members

35 and 35A to the engine 20 using the stay 36 requires a smaller installation space and is advantageous in terms of cost reduction and weight reduction.

Further, in the above-described embodiment, the example in which the engine 20 is used as the drive device of the centrifugal fan 31 is shown, but an electric motor, a hydraulic motor, or the like can be used as the drive device of the centrifugal fan 31.

1 ... Hydraulic excavator (construction machine), 3 ... Upper swing body (car body), 31 ... Centrifugal fan, 31a ... Suction port, 32 ... Bell mouth, 32a ... Outflow port, 35, 35A ... Rectifying member (first rectifying member) , 38 ... Second rectifying member, 41 ... Hub, 42 ... Shroud, 43 ... Blade, 43h ... Connection part with hub, 43s ... Connection part with shroud, 43v ... Apex, 44 ... Front edge, 44h ... With hub Connection part, 44s ... Connection part with shroud, 44v ... Apex, 45 ... Trailing edge, 46 ... Positive pressure surface, 47 ... Negative pressure surface, A ... Rotation axis line, R ... Rotation direction

Claims

A centrifugal fan housed inside the vehicle body,
A bell mouth having an outlet is disposed on the suction side of the centrifugal fan,
The centrifugal fan is
With a hub that can rotate around the axis of rotation,
An annular shroud that is disposed so as to face the hub and forms a flow path between the hub and the suction port,
A plurality of blades provided at intervals in the circumferential direction between the hub and the shroud,
Each of the plurality of blades is
The front edge on the side where air flows in,
The trailing edge on the air outflow side,
A positive pressure surface which is a blade surface on one side extending between the leading edge and the trailing edge and faces the front side with respect to the rotation direction,
It is configured to include a negative pressure surface facing the rear side with respect to the rotation direction, which is the other side blade surface extending between the leading edge and the trailing edge,
In a construction machine in which the outlet of the bell mouth is arranged radially inward of the suction port of the shroud,
In each of the plurality of blades, the front edge has a convex shape on the suction surface side with respect to a line segment that connects a connection portion of the front edge with the hub and a connection portion of the front edge with the shroud. And the apex of the convex shape of the front edge is located radially inward of the wall surface of the outlet of the bell mouth when the suction side of the centrifugal fan is viewed from the axial direction. A construction machine characterized by being formed like this.
The construction machine according to claim 1,
Each of the plurality of blades is configured such that the convex shape of the leading edge extends to the trailing edge,
In each of the plurality of blades, the curvature of the apex in the convex shape of each of the plurality of blades gradually increases from the leading edge toward a middle position between the leading edge and the trailing edge. A construction machine, wherein the construction machine is configured to gradually decrease from a midway position toward the trailing edge.
The construction machine according to claim 1,
Each of the plurality of blades is configured such that the convex shape of the leading edge extends to the trailing edge,
In each of the plurality of blades, the curvature of the apex in the convex shape of each of the plurality of blades is maintained from the leading edge to an intermediate position between the leading edge and the trailing edge, while from the intermediate position. A construction machine, wherein the construction machine is configured to be gradually smaller toward the trailing edge.
The construction machine according to claim 1,
In each of the plurality of blades, the relative position in the circumferential direction of the connection portion with the shroud with respect to the connection portion with the hub in the cross section cut along the cylindrical surface around the rotation axis is from the front edge to the rear edge. Gradually toward the rear side with respect to the rotation direction, the circumferential position of the connecting portion of the trailing edge with the shroud is greater than the circumferential position of the connecting portion of the trailing edge with the hub. A construction machine, wherein the construction machine is configured to be displaced rearward with respect to the rotation direction.
The cooling fan for a construction machine according to claim 1,
Further comprising a first straightening member arranged on the opposite side of the bell mouth with the centrifugal fan interposed therebetween,
The construction machine, wherein the first rectifying member is a member that extends radially outward from at least an outer peripheral edge of the centrifugal fan.
The construction machine according to claim 5,
The construction machine, wherein the first rectifying member is configured such that a portion radially outside the outer peripheral edge of the centrifugal fan is inclined in a direction away from the centrifugal fan with respect to the radial direction.
The construction machine according to claim 5,
Further comprising a second straightening member arranged to face the first straightening member,
The second rectifying member is configured to extend radially outward of an outer peripheral edge of the centrifugal fan, and have a radially outer end portion located closer to the first rectifying member side than a radially inner end portion,
The construction machine, wherein the second rectifying member forms, together with the first rectifying member, an air guide path that guides an airflow discharged from the centrifugal fan.